1. Field of the Invention
The present invention relates to a liquid ejecting apparatus, and a method of controlling the liquid ejecting apparatus during maintenance thereof.
2. Description of Related Art
An ink-jet printer is known as an example of a liquid ejecting apparatus. The ink-jet printer has an ink-jet head having a multiplicity of nozzles for ejecting droplets of an ink, a supply port for receiving the ink supplied from an ink supply source such as an ink reservoir, and an internal passage system connecting the input port to the nozzles.
Such a printer is arranged to perform a maintenance operation such as a purging operation, for maintaining a good condition of ejection of the ink droplets from the head. US 2006/0103700 A1 (corresponding to JP-2006-168339 A) discloses an example of such a maintenance operation, that is, techniques of removing foreign matters such as dust and air bubbles existing within the head, to maintain the head, by performing a purging operation in which the ink is forcibly ejected from the nozzles, and a reverse purging operation in which the ink is pressurized and sucked from the nozzles and discharged from a discharge port.
For maintaining the head, it is considered to suck the ink into the head through the supply port and discharge the ink through the discharge port, without the ink being ejected from the nozzles. During this maintenance operation, it is desirable that meniscus at the nozzles is maintained without destruction due to the maintenance operation. The destruction of the meniscus at the nozzles would result in leakage of the ink from the nozzles, and adhesion of the ink to an ejection surface of the head in which the nozzles are open, giving rise to a risk of contamination of a recording medium and an internal structure of the printer with the ink. Further, the destruction of the meniscus would cause the foreign matters to move toward the nozzles, leading to instability of ejection of the ink droplets from the nozzles, namely, defective ejection of the ink droplets after the maintenance operation.
In the head wherein a filter is provided to divide the internal passage system into an upstream passage portion and a downstream passage portion, as disclosed in the above-disclosed publication US 2006/0103700 A1, it is desirable that the maintenance operation described above does not cause the foreign matters to enter into the downstream passage portion through the filter. The entry of the foreign matters into the downstream passage portion would result in a problem of defective ejection of ink from the nozzles such as failure or instability of the ink ejection.